1. Field of the Invention
The present invention relates to a split band retainer for radially clamping a disk to a spindle hub of a disk drive and more particularly to a split band retainer which is fashioned to permit easy manual or automated assembly of one or more disks to a hub.
2. Description of the Related Art
In a magnetic disk drive one or more disks may be mounted on a spindle hub of a disk drive, the hub being rotated by a motor. In addition, one or more magnetic heads may be mounted on a slider, the slider being mounted on a suspension. The suspension is connected to an actuator which moves each magnetic head to a location adjacent a respective surface of a disk for reading and writing information on the disk. The information is contained in narrow circular tracks that are typically no more than 3 .mu.m wide, and it is important that the active portion of a magnetic head remain within such a narrow track during read and write operations. Lateral movement of the disk with respect to the hub may displace a magnetic head with respect to a track. Such lateral movement is referred to as "radial slip" and the resulting off track performance is referred to as "misregistration". As tracks are narrowed in width to increase disk drive storage density, performance interruptions stemming from misregistration increase. Radial slip and misregistration can occur when shock loading of a disk drive occurs, such as when a laptop computer is dropped.
A disk has a central aperture bounded by an inner annular edge. When the disk is mounted in a drive on a hub, the inner annular edge is spaced from a cylindrical surface of the hub, forming an annular gap therebetween. If the inner annular edge of the disk directly engages the cylindrical hub, temperature changes can cause different expansions and contractions of the disk relative to the hub. This can cause the disk to warp upon compression or disengage the hub upon expansion. In both instances misregistration can occur.
Most disk drives include a retainer disposed in the annular gap between the inner annular edge of the disk and the outer surface of the hub to center the disk on the hub. The retainer also absorbs shock and differential expansion between the disk and the hub.
A primary purpose of the retainer is to permit easy assembly of the disk on the hub. A prior art retainer, which permits easy assembly, is described in Patent Cooperation Treaty (PCT) Application No. WO 93/26006", published 23 Dec. 1993. This retainer employs a corrugated split band in the annular gap for mounting a plurality of disks on a hub. During assembly, the corrugated split band is biased inwardly toward the hub, disks are disposed about the corrugated band, and then the corrugated band is released so that the corrugations spring mount the disks to the hub. While this retainer permits easy assembly it would be desirable to more rigidly mount the disks to the hub and to reduce weight by providing discrete retainers instead of a single cylindrical retainer which extends along the hub between the disks.
A retainer should also provide a predictable predetermined radial clamping pressure between disk and hub. This pressure should be distributed about the inner annular edge of the disk.
There is a strong felt need for a disk to hub retainer which permits easy manual or automated assembly of the disk on the hub, which is discrete with respect to each disk and which applies predictable radial clamping pressure which is distributed about the inner annular edge of the disk.